The present invention relates to a strobe device, incorporated with a silver-halide camera, a lens-fitted film unit and a digital camera, and specifically, relates to a strobe device which is suitable for a camera equipped with a wide angle lens, an image capturing apparatus equipped with a strobe device and a reflector of the strobe light.
FIG. 1 shows distribution characteristics of the luminous intensity for a conventional strobe device. As shown in FIG. 1, in a conventional strobe device, luminous intensity of strobe lighting is substantially constant within a predetermined illuminating angle, or the luminous intensity at the center position is greater than that at the peripheral positions, so as to increase the guide number in regard to the illuminating distance along the center axis.
In the distribution characteristics of the luminous intensity described above, however, when capturing a subject, like as a flat surface, directly opposite the camera or subjects aligned in the vertical direction, the larger the angle of view, the larger the distance between the peripheral subject and the strobe device, and thereby, luminous intensity for the peripheral subject would decrease due to the low of inverse square, and the reflected light from the subject would also decrease according as the distance becomes larger.
In addition, the amount of light components, coming toward the camera after being reflected and scattered on a plane object such as a wall, etc., would also decrease, due to the large angle of incident of the light illuminated by the strobe device.
Further, since the peripheral subjects are usually located at distant positions in almost all conventional snapshot images, compared to the subject located in the center position, the reflected light intensity from such peripheral subjects will decrease considerably.
Owing to the multiple-effects of the adverse factors mentioned above, the periphery portion is apt to be dark in the photograph shot with conventional strobe lighting, resulting in a lack of liveliness, in which only the center portion is remarkably bright, while the periphery portion is a flat and expressionless field. This tendency will become remarkable according as the illuminating angle of strobe device is getting larger with the increase of the angle of view, by employing a wide-angle lens for the camera.
Now, referring to FIG. 6, an example of the relationship, between viewing angle a of a photographic lens in a camera employing a strobe device and illuminating angle xcex2 of the light coming to subject M from the strobe device, will be described in the following.
As shown in FIG. 6(a), when viewing angle a is relatively small (for instance, 60 degrees) as a standard type, it is possible to adequately illuminate subject M existing within viewing angle a, even if illuminating angle xcex2 of the strobe device is not so wide.
As shown in FIG. 6(b), however, when a wide-angle photographic lens having a wide viewing angle a (for instance, 90 degrees) is employed in the camera, it becomes almost impossible to adequately illuminate the overall region covered by viewing angle a with illuminating angle xcex2 of a conventional strobe device, resulting in difficulties of improving photographic effects of subject M.
To overcome the abovementioned drawbacks in conventional strobe devices, it is an object of the present invention to provide a strobe device, which could brightly illuminate a periphery of the subject and, specifically, makes it possible to obtain a desirable distribution characteristics of the luminous intensity, even when an image capturing is conducted with a wide-angle photographic lens.
Accordingly, to overcome the cited shortcomings, the abovementioned objects of the present invention can be attained by strobe devices and image capturing apparatus described as follow.
(1) A strobe device, comprising a reflector to reflect a strobe light, a light-emitting tube, mounted in an interior of the reflector, to emit the strobe light and an optical panel, mounted in front of the light-emitting tube, to transmits the strobe light, wherein a maximum luminous intensity of the strobe light, illuminated by the strobe device, is arranged in a direction being different from a direction of a strobe light axis which is orthogonal to a longitudinal direction of the light-emitting tube.
(2) The strobe device of item 1, which fulfills a following conditional equation,
xe2x80x83[4xc3x97{(cos(KP))xe2x88x924xe2x88x921}xc3x97QC]+QCxe2x89xa7QKPxe2x89xa7[0.1xc3x97{(cos(Kp))xe2x88x924xe2x88x921}xc3x97QC]+QC
where: KP; an illumination angle for the maximum luminous intensity with reference to the strobe light axis, QC; a luminous intensity in a direction of the strobe light axis QKP; the maximum linous intensity.
(3) The strobe device of item 1, wherein the reflector comprises a concave reflection surface and a side reflection surface arranged at each side of the concave reflection surface, the side reflection surface is inclined to the light-emitting tube at such an angle that the side reflection surface reflects the strobe light, emitted from the light-emitting tube, so as to emit the strobe light toward a direction of being apart from the strobe light axis located at a center of the light-emitting tube, instead of toward a direction of crossing the strobe light axis.
(4) The strobe device of item 3, wherein each of the side reflection surfaces comprises a sub-reflection surface being orthogonal to a longitudinal direction of the light-emitting tube.
(5) The strobe device of item 1, which fulfills a following conditional equation,
1.5xe2x89xa6W/Lxe2x89xa62.0,
where: L; an effective illuminating length of the light-emitting tube, W; a length of the strobe panel in a longitudinal direction of the light-emitting tube.
(6) The strobe device of item 1, wherein the light-emitting tube is formed in a cylindrical shape and the reflector comprises a concave reflection surface, the strobe device fulfills following conditional equations,
3.0U less than W1 less than 5.2U
1.2U less than W2 less than 3.5U
2U less than D less than 5U
where: W1; a width at a front end of the concave reflection surface, W2; a width of the concave reflection surface at a center axis of the light-emitting tube, D; a distance from a front end of the concave reflection surface to a center axis of the light-emitting tube, and U; a distance from a center axis of the light-emitting tube to a rear end of the concave reflection surface.
(7) The strobe device of item 1, wherein the light-emitting tube is formed in a cylindrical shape and the reflector comprises a concave reflection surface, and in regard to a cross-sectional view of the concave reflection surface in a direction orthogonal to a longitudinal direction of the light-emitting tube, when a front end point of the concave reflection surface, an intersection of the concave reflection surface and a straight line, which goes through a center axis of the light-emitting tube and is perpendicular to the strobe light axis, and a rear end point of the concave reflection surface on the strobe light axis, are defined as P, Q and V, respectively, all of points, residing on the concave reflection surface between points P and Q, are located opposite a center axis of the light-emitting tube with respect to a line P-Q, while all of points, residing on the concave reflection surface between points Q and V, are located opposite a center axis of the light-emitting tube with respect to a line Q-V, and under the above condition, the strobe device fulfills following conditional equations,
0.05 less than xcex941/U less than 0.4
0.07 less than xcex942/U less than 0.5
where: xcex941; a maximum distance from a point, residing on the concave reflection surface between points P and Q, to the line P-Q, xcex942; a maximum distance from a point, residing on the concave reflection surface between points Q and V, to the line Q-V, and U; a distance from a center axis of the light-emitting tube to a rear end of the concave reflection surface.
(8) The strobe device of item 6, wherein the light-emitting tube is apart from the concave reflection surface.
(9) The strobe device of item 6, which fulfills a following conditional equation,
0.5 less than T/U less than 1.5
where: T; an outer diameter of the light-emitting tube.
(10) The strobe device of item 1, wherein the optical panel comprises a light diverging section, located at a center area in a longitudinal direction of the light-emitting tube, to diverge the strobe light toward periphery, the light diverging section comprises at least one of such surfaces as a Fresnel lens, a negative lens and a row of prisms.
(11) The strobe device of item 10, wherein, in a longitudinal direction of the light-emitting tube, a length of the light diverging section is 90%-120% of a length of the light-emitting tube located within an interior of the reflector.
(12) The strobe device of item 10, wherein, in a longitudinal direction of the light-emitting tube, a length of the light diverging section is 70%-120% of a length of the light-emitting tube located within an interior of the reflector.
(13) The strobe device of item 1, wherein the strobe device exhibits a maximum luminous intensity within a range of viewing angle in a direction of at least one of a long side, a short side and a diagonal of a photographed image frame projected by a photographic lens, which is incorporated in an image capturing apparatus equipped with the strobe device.
(14) The strobe device of item 1, wherein the strobe device exhibits a maximum luminous intensity without a range of viewing angle in a direction of at least one of a long side, a short side and a diagonal of a photographed image frame projected by a photographic lens, which is incorporated in an image capturing apparatus equipped with the strobe device.
(15) The strobe device of item 13, which fulfills a following conditional equation,
(4/3)xc3x97Axe2x89xa7KPxe2x89xa7(1/5)xc3x97A
where: A; a half viewing angle of the photographic image frame in a predetermined direction, KP; an illumination angle for the maximum luminous intensity in the predetermined direction with reference to the strobe light axis.
(16) An image capturing apparatus, comprising a photographic lens and a strobe device, which comprises a reflector to reflect a strobe light forward, a light-emitting tube, mounted in an interior of the reflector, to emit the strobe light, and an optical panel, mounted in front of the light-emitting tube, to transmits the strobe light, wherein a maximum luminous intensity of the strobe light, illuminated by the strobe device, is arranged in a direction being different from a direction of a strobe light axis which is orthogonal to a longitudinal direction of the light-emitting tube.
(17) The image capturing apparatus of item 16, which fulfills a following conditional equation,
[4xc3x97{(cos(KP))xe2x88x924xe2x88x921}QC]+QCxe2x89xa7QKPxe2x89xa7[0.1xc3x97{(cos(KP))xe2x88x924xe2x88x921}xc3x97QC]+QC
where: KP; an illumination angle for the maximum luminous intensity with reference to the strobe light axis, QC; a luminous intensity in a direction of the strobe light axis, QKP; the maximum luminous intensity.
(18) The image capturing apparatus of item 16, wherein the reflector comprises a concave reflection surface and a side reflection surface arranged at each side of the concave reflection surface, the side reflection surface is inclined to the light-emitting tube at such an angle that the side reflection surface reflects the strobe light, emitted from the light-emitting tube, so as to emit the strobe light toward a direction of being apart from the strobe light axis located at a center of the optical panel, instead of toward a direction of crossing the strobe light axis.
(19) The image capturing apparatus of item 16, wherein the light-emitting tube is formed in a cylindrical shape and the reflector comprises a concave reflection surface, the strobe device fulfills following conditional equations,
xe2x80x833.0U less than W1 less than 5.2Uxe2x80x83xe2x80x83(1)
1.2U less than W2 less than 3.5Uxe2x80x83xe2x80x83(2)
2U less than D less than 5Uxe2x80x83xe2x80x83(3)
where: W1; a width at a front end of the concave reflection surface, W2; a width of the concave reflection surface at a center axis of the light-emitting tube, D; a distance from a front end of the concave reflection surface to a center axis of the light-emitting tube, and U; a distance from a center axis of the light-emitting tube to a rear end of the concave reflection surface.
(20) The image capturing apparatus of item 16, wherein the optical panel comprises a light diverging section, located at a center area in a longitudinal direction of the light-emitting tube, to diverge the strobe light toward periphery, the light diverging section comprises at least one of such surfaces as a Fresnel lens, a negative lens and a row of prisms.
(21) The image capturing apparatus of item 16, wherein the strobe device exhibits a maximum luminous intensity within a range of viewing angle in a direction of at least one of a long side, a short side and a diagonal of a photographed image frame projected by the photographic lens.
(22) The image capturing apparatus of item 16, wherein the strobe device exhibits a maximum luminous intensity without a range of viewing angle in a direction of at least one of a long side, a short side and a diagonal of a photographed image frame projected by the photographic lens.
(23) The image capturing apparatus of item 16, which fulfills a following conditional equation,
(4/3)xc3x97Axe2x89xa7KPxe2x89xa7(1/5)xc3x97A
where: A; a half viewing angle of the photographic image frame in a predetermined direction, KP; an illumination angle for the maximum luminous intensity with reference to the strobe light axis.
(24) The image capturing apparatus of item 16, wherein the image capturing apparatus is a lens-fitted film unit equipped with the strobe device.
(25) The image capturing apparatus of item 16,
wherein the image capturing apparatus is a silver-halide film camera equipped with the strobe device.
Further, to overcome the abovementioned problems, other strobe devices and image capturing apparatus, embodied in the present invention, will be described as follow:
(26) A strobe device, characterized in that a strobe light, emitted to a subject within a predetermined range, has a maximum luminous intensity in a range corresponding to a viewing angle at least at one of a long side, a short side and a diagonal of a photographed image frame formed by a photographic lens, in a direction being different from a direction of a strobe light axis which is parallel to a optical axis of the photographic lens.
(27) The strobe device of item 26, characterized in that the strobe device fulfills a following conditional equation, when a luminous intensity emitted in a direction of the strobe light axis, an illumination angle for the maximum luminous intensity with reference to the strobe light axis, and the maximum luminous intensity are defined as QC, KP and QKP, respectively.
[4xc3x97{(cos(KP))xe2x88x924xe2x88x921}xc3x97QC]+QCxe2x89xa7QKPxe2x89xa7[0.1xc3x97{(cos(KP))xe2x88x924xe2x88x921}xc3x97QC]+QC
(28) The strobe device of item 26, characterized in that the strobe device fulfills a following conditional equation, when a luminous intensity emitted in a direction of the strobe light axis, an illumination angle for the maximum luminous intensity with reference to the strobe light axis, and the maximum luminous intensity are defined as QC, KP and QKP, respectively.
[2xc3x97{(cos(KP))xe2x88x924xe2x88x921}xc3x97QC]+QCxe2x89xa7QKPxe2x89xa7[0.1xc3x97{(cos(KP))xe2x88x924xe2x88x921}xc3x97QC]+QC
(29) The strobe device described in one of items 26-28, characterized in that the illumination angle (KP degree) for the maximum luminous intensity with reference to the strobe light axis fulfills a following conditional equation, when a predetermined half viewing angle of the photographic image frame is defined as A degree.
xe2x80x83(4/3)xc3x97Axe2x89xa7KPxe2x89xa7(1/5)xc3x97A
(30) The strobe device described in one of items 26-28, characterized in that the illumination angle (KP degree) for the maximum luminous intensity with reference to the strobe light axis fulfills a following conditional equation, when a predetermined half viewing angle of the photographic image frame is defined as A degree.
(9/10)xc3x97Axe2x89xa7KPxe2x89xa7(1/5)xc3x97A
(31) The strobe device described in one of items 26-28, characterized in that the illumination angle (KP degree) for the maximum luminous intensity with reference to the strobe light axis fulfills a following conditional equation, when a predetermined half viewing angle of the photographic image frame is defined as A degree.
(9/10)xc3x97Axe2x89xa7KPxe2x89xa7(1/2)xc3x97A
(32) The strobe device described in one of items 26-31, characterized in that the strobe light has a maximum luminous intensity in a range corresponding to the viewing angle at the long side of the photographed image frame in a direction being different from a direction of the strobe light axis which is parallel to the optical axis of the photographic lens.
(33) The strobe device of item 32, characterized in that the illumination angle (KP degree) for the maximum luminous intensity with reference to the strobe light axis fulfills a following conditional equation, when the half viewing angle of the long side of the photographic image frame is defined as AL degree.
(4/3)xc3x97ALxe2x89xa7KPxe2x89xa7(1/5)xc3x97AL
(34) A strobe device, characterized in that a strobe light, emitted to a subject within a predetermined range, has a maximum luminous intensity in a direction being larger than a viewing angle at least at one of a long side, a short side and a diagonal of a photographed image frame formed by the photographic lens.
(35) A strobe device, characterized in that the strobe device comprises a concave reflection surface to reflect a light emitted from a light-emitting tube and a side reflection surface arranged at each side of the concave reflection surface, and an angle of the side reflection surface versus the light-emitting tube is set at such an angle that the side reflection surface reflects the light, emitted from the light-emitting tube, in a direction of being apart toward both sides of the light-emitting tube.
(36) The strobe device of item 35, characterized in that the side reflection surface comprises a sub-reflection surface, which is orthogonal or substantially orthogonal to the light-emitting tube and is located at the protruded end of the side reflection surface.
(37) The strobe device of item 35 or item 36, characterized in that the strobe device fulfills a following conditional equation, when a length of an effective light-emitting section of the light-emitting tube and a length of a strobe panel, arranged in front of the concave reflector surface and both of the side reflection surfaces, along the longitudinal direction of the light-emitting tube, are defined as L and W.
1.5xe2x89xa7W/Lxe2x89xa72.0,
(38) A camera, equipped with a strobe device, characterized in that the camera comprises the strobe device to illuminate a subject with a light emitted from a light-emitting tube, and the strobe device comprises a concave reflection surface to reflect the light emitted from the light-emitting tube and a side reflection surface arranged at each side of the concave reflection surface, and an angle of the side reflection surface versus the light-emitting tube is set at such an angle that the side reflection surface reflects the light, emitted from the light-emitting tube, in a direction of being apart from a direction being orthogonal to the light-emitting tube.
(39) The camera, equipped with a strobe device, of item 38, characterized in that the side reflection surface comprises a sub-reflection surface, which is orthogonal or substantially orthogonal to the light-emitting tube and is located at the protruded end of the side reflection surface.
(40) A lens-fitted film unit, equipped with a strobe device, characterized in that the lens-fitted film unit, in which an unexposed film is loaded beforehand, comprises the strobe device to illuminate a subject with a light emitted from a light-emitting tube, and the strobe device comprises a concave reflection surface to reflect the light emitted from the light-emitting tube and a side reflection surface arranged at each side of the concave reflection surface, and an angle of the side reflection surface versus the light-emitting tube is set at such an angle that the side reflection surface reflects the light, emitted from the light-emitting tube, in a direction of being apart from a direction being orthogonal to the light-emitting tube.
(41) The lens-fitted film unit, equipped with a strobe device, of item 40, characterized in that the side reflection surface comprises a sub-reflection surface, which is orthogonal or substantially orthogonal to the light-emitting tube and is located at the protruded end of the side reflection surface.
(42) A light-sealing structure, characterized in that the light-sealing structure seals a light entering into a joint region of both members by joining a convex portion formed on one of members with a concave portion formed on another member, and a rough-forging section is formed on at least one of surfaces of the convex portion and the concave portion.
(43) The light-sealing structure of item 42, characterized in that a top-end surface of the convex portion at one of members contacts a bottom of the concave portion at the other member.
(44) The light-sealing structure of item 42 or item 43, characterized in that a rise angle of convex portion at one of members and a fall angle of concave portion at the other member are set at an angle in a range of 3xc2x0-45xc2x0, respectively.
(45) The light-sealing structure described in one of items 42-44, characterized in that the height of convex portion at one of members and the depth of concave portion at the other member are set at a size in a range of 0.3 mm-1.5 mm, respectively.
(46) The light-sealing structure described in one of items 42-45, characterized in that the one member having the convex portion and the other member having the concave portion are arranged at such a position as facing a film conveyance region of an opt-photographic apparatus which captures images on the film.
(47) A strobe device, characterized in that, in the strobe device comprising a light-emitting tube formed in a cylindrical shape and a reflector, a cross-sectional shape of an inner surface of the reflector in a direction orthogonal to a longitudinal direction of the light-emitting tube fulfills following conditional equations.
3.0U less than W1 less than 5.2U
1.2U less than W2 less than 3.5U
2U less than D less than 5U
where: W1; a width at a front end, W2; a width at a center axis of the light-emitting tube, D; a distance from a front end of to a center axis of the light-emitting tube, and U; a distance from a center axis of the light-emitting tube to a rear end.
(48) The strobe device of item 47, characterized in that, the following conditional equations are fulfilled.
3.0U less than W1 less than 4.7U
1.2U less than W2 less than 3.2U
2U less than D less than 5U
(49) The strobe device of item 48, characterized in that the following conditional equations are fulfilled.
3.2U less than W1 less than 4.0U
2.0U less than W2 less than 3.0U
2.5U less than D less than 4U
(50) The strobe device described in one of items 47-49, characterized in that, in regard to a cross-sectional shape of the concave reflection surface at both sides centered on a strobe light axis, when a front end point, an intersection with a straight line, which goes through a center axis of the light-emitting tube and is perpendicular to the strobe light axis, and a rear end point on the strobe light axis, are defined as P, Q and V, respectively, all of points, residing between points P and Q, are located opposite a center axis of the light-emitting tube with respect to a line P-Q, while all of points, residing between points Q and V, are located opposite a center axis of the light-emitting tube with respect to a line Q-V, and, when a maximum distance from a point, residing between points P and Q, to the line P-Q and a maximum distance from a point, residing between points Q and V, to the line Q-V are defined as xcex941 and xcex942, respectively, the following conditional equations are fulfilled.
0.05 less than xcex941/U less than 0.4
0.07 less than xcex942/U less than 0.5
(51) The strobe device of item 50, characterized in that the following conditional equations are fulfilled.
0.1 less than xcex941/U less than 0.3
0.12 less than xcex942/U less than 0.3
(52) The strobe device described in one of items 47-50, characterized in that the light-emitting tube is apart from the concave reflection surface.
(53) The strobe device described in one of items 47-51, characterized in that the following conditional equation is fulfilled, when an outer diameter of the light-emitting tube is defined as T.
0.5 less than T/U less than 1.5
(54) A strobe device, characterized in that, in the strobe device which comprises a light-emitting tube formed in a cylindrical shape and a optical panel mounted in front of a reflector, the optical panel comprises a light diverging section, located at a center area of the optical panel, to diverge a light beam toward periphery, and the light diverging section comprises such surfaces as a Fresnel lens, a negative lens and a row of prisms, in which a plurality of prisms are arranged in parallel.
(55) The strobe device of item 54, characterized in that a length of the light diverging section in a longitudinal direction of the light-emitting tube is formed as substantially the same length of the light-emitting tube positioned in an interior of the reflector in a longitudinal direction of the light-emitting tube.
(56) The strobe device of item 54, characterized in that a length of the light diverging section in a longitudinal direction of the light-emitting tube is 90%-120% of a length of a light-emitting section at which the light-emitting tube emits a light in a longitudinal direction.
(57) The strobe device described in one of items 54-56, characterized in that the light diverging section is either a Fresnel surface or a row of prisms, which is arranged in parallel only in a direction orthogonal to the longitudinal direction of the light-emitting tube.
(58) The strobe device described in one of items 54-57, characterized in that a flat surface section is formed at the center of the light diverging section.
(59) The strobe device described in one of items 54-57, characterized in that a concave cylindrical lens surface, a centerline of which is arranged in a direction parallel to the longitudinal direction of the light-emitting tube, is formed at the center of the light diverging section
(60) The strobe device described in one of items 54-59, characterized in that a peripheral section of the light diverging section in the optical panel is formed as a flat surface.
(61) The strobe device described in one of items 54-59, characterized in that a peripheral section of the light diverging section in the optical panel is formed as either a Fresnel surface or a row of prisms, which is parallel to the longitudinal direction of the light-emitting tube.
(62) The strobe device described in one of items 54-59, characterized in that a peripheral section of the light diverging section in the optical panel is formed as a concave cylindrical lens surface, a centerline of which is arranged in a direction parallel to the longitudinal direction of the light-emitting tube.
(63) The strobe device described in one of items 54-62, characterized in that the light diverging section of the optical panel is arranged at the surface faced to the light-emitting tube.
(64) The strobe device described in one of items 54-63, characterized in that, when assuming an imaginary surface which is orthogonal to the longitudinal direction of the light-emitting tube, a tilted-surface having an area being more than xc2xd of the inner sidewall area of the reflector, located opposite the imaginary surface, inclines at an angle being more than 40xc2x0 with respect to the imaginary surface.